Improved drill



UNITED STATES PATENT OFFICE.

, E. e. wELLs, 0E PLUMEE, PENNSYLVANIA.

I'MPROVED DRILL.

Specification forming part of Letters Patent No. 48,609, dated July 4, 1865.

To all whom it may concern:

Beitknownthat I, R. G. WELLs, ot' Plumer, in the county of Venango and State of Penn- Sylvania, have invented a new and lmproved Drill; and I do hereby declare that the following is a full and exact description thereof, reference being had to the accompanying drawing substantially as shown in Fig. 8, the cutting-edge extends from diagonally-opposite cornersv a a., the middle portion, b, forming a slight double curve, more orless nearly approaching a straight line. The two other corners, c c, ot' the drill are beveled oft' to the proper angle, the bevel gradually running out as it approaches the corners a c, where, for a little distance, the sides of the drill are nearly vertical or continuousv with the unbeveled portion thereof. This makes the opposite cuttin g-ed ges at a a, for a s'mall portion of the width ot' the drill, nearly or quite straight, and in the planes ot' the sides ofthe drill.

It will be seen by this constructionthat only the very center of the drill-edge b has an equal bevel on both sides, while the diagonally-opposite corners c c are most beveled, and coincide in their action against the other two corners, a a, which coincide in their action on the movements of the drill.

The principaleft'ects and advantages of this construction are, first, the drill is in a measure self-sharpening, because the wear is principally on the bevel corners cc, so thatthe middleedge, b, is left not only not so much dulled, but partially sharpened by the said wear of the bevels; second, the bevels being continuous and regu- ]ar in form, the drill is even rather more easily sharpened, either by forging or grinding, than the common form ot' drill; third, the drill has a tendency to give a cleaving or shaving cut in the rock, because the beveled sides being opposed in action to the straight sides, and having a tendency to yield, and to throw the chippings in that direction, the cutting-corners a a cleave oft' the rock obliquely in that direction, thereby rendering the action of drilling more easy and rapid than that ofthe common form ot' drill, which has no tendency to turn in either direction; fourth, this tendency of the drill to turn continually to the left has the effect to keep the drill tightly screwed onto the drillrod, which is ordinarily attached to the drill by a right-hand screw; hence there is no danger of its ever becoming disconnected from the rod, as the common drills have, causing much loss of time and consequent expense.

What l claim as my invention, and desire to secure by Letters Patent, is-

Forming the drill with the diagonal edge b, and diagonally-opposite straight corners a a, and alternate beveled corners c c, substantially as and for the purposes herein specified.

R. G. WELLS.

Witnesses: LEWIS VAN ANDEN, RICHARD F. HUNT. 

